<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
</head>
<style>
  html{
    width: 100%;
    height: 100%;
    overflow: hidden;
    font-style: sans-serif;
  }
  body{
    width: 100%;
    height: 100%;
    font-family: 'Open Sans',sans-serif;
    margin: 0;
    background-color: #4A374A;
  }
  #login{
    position: absolute;
    top: 50%;
    left:50%;
    margin: -150px 0 0 -150px;
    width: 300px;
    height: 300px;
  }
  #login h1{
    color: #fff;
    text-shadow:0 0 10px;
    letter-spacing: 1px;
    text-align: center;
  }
  h1{
    font-size: 2em;
    margin: 0.67em 0;
  }
  input{
    width: 278px;
    height: 18px;
    margin-bottom: 10px;
    outline: none;
    padding: 10px;
    font-size: 13px;
    color: #fff;
    text-shadow:1px 1px 1px;
    border-top: 1px solid #312E3D;
    border-left: 1px solid #312E3D;
    border-right: 1px solid #312E3D;
    border-bottom: 1px solid #56536A;
    border-radius: 4px;
    background-color: #2D2D3F;
  }
  .but{
    width: 300px;
    min-height: 20px;
    display: block;
    background-color: #4a77d4;
    border: 1px solid #3762bc;
    color: #fff;
    padding: 9px 14px;
    font-size: 15px;
    line-height: normal;
    border-radius: 5px;
    margin: 0;
  }
</style>
<body>

<div id="login">
  <h1>Login</h1>
  <form id="ifrom">
    <input type="text" name="user_account" required="required" placeholder="用户名" name="u"></input>
    <input type="password" name="user_password" required="required" placeholder="密码" name="p"></input>
    <button class="but" type="button" id="btn">登录</button>
  </form>
</div>
</body>
<script>

    var btn = function(){
        $.ajax({
            async:false,//是否异步请求
            url:"/user/login",//请求地址
            type:"POST",//请求方式
            data:$("#ifrom").serialize(),//表单序列化
            dataType:"json",//指定返回数据类型
            success:function(data){
                //把JSON转成字符串
                //JSON.stringify(data)
                //把字符串转成JSON,Notation
                //alert("success:"+JSON.parse(data));
                if(data.code == 1){
                    alert(data.msg);
                    location.href = "main.html";
                }
            },
            error:function(data){
                alert("error:"+data);
            }
        });
    }
    //$("#btn")选择器,选择了id为btn的标签
    $("#btn").click(btn);
</script>
</html>